District heating. 
 An outdated legacy or a European future?

It is said that a child should not be cornered, as this creates a sense of sadness, hopelessness and takes away hope for the future. When receiving heat bills, a significant part of the country's population feels like children cornered. Heat supply is a socially sensitive area. Heat bills seriously affect the lives of many families. More than a third of a family's budget for utilities (which is mainly heat energy) is too much. The level of civilised countries is no more than 7-10%. Electricity, water, and natural gas can be saved, but heat energy for heating is still not, because there is nothing to control and regulate its consumption in individual apartments in most apartment buildings. One cannot envy the mayor of the city, who has a huge technical system that is clearly outdated, and the cost of modernisation is ten times higher than the city's development budget. Where to get this kind of money? Solving this issue will require a long and painstaking work with domestic and international financial institutions. There is a simpler way: provide each family with an electric heater or gas boiler, slightly modernise the house electricity and gas supply systems, and the problem is solved. And then: rescuing drowning people is the job of the drowning people themselves. In some cities, this is what they do. However, both gas and electricity will become more expensive. Even with austerity measures, half of a family's budget may not be enough for electric heating. The closure of district heating systems instead of their modernisation with the use of modern high-efficiency technologies deprives us of the prospect of receiving heat energy at an affordable price, and the state of Ukraine of energy independence and security. Ukrainian heat supply is a tangle of technical, technical and economic, regulatory, social and financial problems.             

Some problems exacerbate others, which in turn give rise to others, and as a result, form a vicious circle. An example is a typical chain of cause and effect: consumers are not satisfied with the price/quality ratio - they disconnect from the district heating system - sales of heat energy fall - the economic performance of heat supply companies deteriorates - the tariff needs to be increased - the process of disconnecting consumers from the district heating system intensifies. Another contradiction: DHCs are created for decades, while the period between elections of representatives of central and local authorities is no more than five years. Hence the temptation to make quick, outwardly spectacular (but not effective) decisions. For example, fragmentary modernisation of the district heating system, when a tasty object (hospital, kindergarten, educational institution) is disconnected from the city system, installing an efficient heat source, which, of course, belongs to a private owner, and reporting high energy efficiency. 

And the negative consequences for the city's heating system in general, associated with underutilisation of the city's powerful heat sources, remain behind the scenes. Thus, there are many problems, but one key one is the low energy efficiency of existing district heating systems. To solve this problem, urgent and active government intervention is required, as discussed below. We are among the leaders, but we are rapidly losing ground Ukraine has traditionally been among the leading countries in the field of district heating. In 1991, we were second only to Russia in terms of production volumes. In recent years, however, we have been overtaken by our European neighbours: Latvia, Estonia, Poland, not to mention Denmark, the leader in district heating development. Today, about half of the heated area of all buildings in our country is connected to the district heating system. Five years ago, this figure was 60%, and 30 years ago it was 63%, the same as in Denmark today. The volume of heat production in the DH sector is declining rapidly. Over the years of independence, too little has been created in Ukraine's district heating sector. 

What is being done is an attempt to maintain the old system in a technically sound condition. But it is not working well. This is eloquently evidenced by hot water flowing on the sidewalks and cars sinking underground at the beginning of the heating season. The energy-efficient modernisation of the district heating sector in our country has not yet begun. And Europe is already implementing fourth-generation district heating systems. But more on that below. For now, let's get back to the Ukrainian reality. The powerful Ukrainian DHS (Kyiv's system ranks third in the world in terms of capacity) is being replaced by house and apartment gas and electric boilers and boilers. We are becoming more and more tied to expensive natural gas and electricity and are losing potential opportunities to use other, cheaper energy sources.   

Reliability of SCR, especially pipelines, is catastrophically reduced. The quality of heat supply suits few people. What is "insufficient heating," "too much heating," a painful expectation of turning on the heating in October, all users of district heating felt for themselves. The monuments to the leaders of socialism were demolished, the streets were renamed, but we do not have time to modernize the outdated Soviet systems, which honestly served their purpose. Why Europe is developing district heating In 2010 in the EU, the share of district heating was only 10%, but it is planned that by 2030 this figure will increase to 30%, and by 2050 - up to 50%. Why are EU countries so actively developing SCT? There are several reasons: diversification of heat energy sources, increase of energy independence of the country, possibility to get cheap heat energy, reduction of harmful emissions. Already, the share of traditional gas boilers in the SCT of European countries does not exceed 20% (in Ukraine - about 60%). 

Until 2050 the share of such boilers will not exceed 10%. The main sources of thermal energy are combined production of electric and thermal energy (cogeneration), solid household waste, biofuels, solar energy, geothermal energy, thermal energy of seas, reservoirs, urban sewage, ventilation emissions, waste heat energy of industrial enterprises. Diversification makes it possible to jump off the gas needle, use its own natural, agricultural, industrial resources, implement the principle of "waste to energy," increase energy independence and security of the country. Today, in European countries, especially in Denmark, fourth-generation SCTs are being introduced, the characteristic features of which are: the use of a low-temperature coolant, which makes it possible to usefully use urban heat emissions; integration of energy sources into a single network; providing access to the integrated heat network of independent heat energy suppliers; dynamic interaction between suppliers and consumers of thermal energy; active participation of SCR in the regulation of electrical loads of the power system; the ability to be an integral part of integrated intelligent systems, in particular cooling systems; possibility to provide control structures with necessary information for cost planning, operation mode, strategic investments. 

Waste to energy The district heating system should be considered not only as a source of heat energy, but also as an urban recycling system, with the help of which it is possible to convert human waste products into energy. At the same time solve energy and environmental problems. The main products of human life, inevitably formed in each city, are solid household waste, silt sediments, as well as warm water of sewage. Together, they can provide 40% of the city with thermal energy for heating, and if we insulate our cold houses, then by 90%. Unfortunately, there is currently only one incinerator in Ukraine (in Kyiv) that supplies thermal energy to the SCT. This direction should be developed by applying European experience. In Europe, 7% of waste is used for heat supply. In some countries, this figure is significantly higher: in Switzerland - 44%, France - 26, Sweden - 24%. 

For heat supply of industrial cities, such as Zaporozhye, Mariupol, Alchevsk, waste heat energy of industrial enterprises should be used. Already in Zaporozhye, waste heat energy of the Zaporozhstal metallurgical plant is used to prepare hot water. However, this is only a small part of the available potential of waste thermal energy of the enterprise. Within the framework of the USAID project "Municipal Energy Reform in Ukraine," an energy audit of a number of cities was carried out - Kyiv, Zaporozhye, Odessa, Vinnitsa, Lviv, Chernihiv, Bila Tserkva and preliminary feasibility studies were developed for projects for obtaining heat energy cheaper than in gas boilers. They should be implemented. Combined production of electric and thermal energy (cogeneration) allows to reduce fuel consumption by 10-30% in comparison with separate production of these types of energy. 

According to the Directive 2012/27ЄS efficient district heating and cooling systems are systems that use at least 50% of renewable energy, 50% of secondary thermal energy resources, 75% of the heat of cogeneration or 50% of the heat from these sources. Unfortunately, there are no such systems in Ukraine yet. At the same time, the unrealized potential of cogeneration production of Ukrainian power plants is the basis that will help us create energy-efficient SCRs as soon as possible. The installed thermal capacity of the turbine units of thermal power plants, thermal power plants and nuclear power plants of Ukraine is several times higher than the needs for thermal energy of the SCT. Unfortunately, the existing cogeneration plants in Ukraine not only do not grow by new consumers, but also steadily lose the market for thermal energy. For 1990-2018 cogeneration supply of thermal energy fell four times (in parallel with a decrease in the total supply of thermal energy from the SCR). Why is cogeneration developing in Europe and fading in Ukraine? One of the reasons lies in outdated approaches to the distribution of savings from combined production between electric and thermal energy. In Ukraine, it is traditionally attributed mainly to electric energy. The estimated efficiency of thermal energy production in modern cogeneration plants according to outdated methods is often less than in gas boilers, which hinders the development of cogeneration in the country. The well-known scientific and methodological problem of the objective distribution of fuel costs between electric and thermal energy was successfully solved at the beginning of this century at the National Academy of Sciences of Ukraine. 

But the developed recommendations are still optional, which makes it impossible to actively implement modern cogeneration technologies. It is necessary to give the developed recommendations the status of a mandatory regulatory and technical document. There are other factors that limit the development of cogeneration in Ukraine, a detailed analysis of which goes far beyond the scope of the problem under consideration and is the subject of a separate article that we plan to prepare. The problems of cogeneration should be solved using European experience (primarily Denmark and Germany) and taking into account our realities. However, the basic role of cogeneration in the transformation of outdated Ukrainian SCRs into modern energy efficient systems is undoubted. Energy of the sun and the environment These sources use a free energy resource and do not pollute the environment with harmful emissions. In Ukraine, thanks to incentive pricing, solar power plants are actively being introduced. 
However, there are no large centralized solar sources of thermal energy. In Europe in 2017 196 solar thermal capacities worked with a total installed capacity of 36 MW. These units are used together with heat accumulators. A promising direction for the introduction of energy-efficient SCR in the coastal cities of Ukraine is the use of low-potential thermal energy of the Black Sea, the temperature of the deep layers of water in which does not fall below 9 ° C in winter. A well-known example of such a system is the world's largest seawater heat pump station with an estimated temperature of + 3 ° C VKrtan Ropsten (Stockholm, Sweden) with a capacity of 180 MW. Employees of the Institute of Gas and the Institute of Technical Thermophysics of the National Academy of Sciences of Ukraine developed a technical and economic proposal for the use of the heat of the Black Sea for heating the central part of Odessa. The proposal is based on the integrated use of heat pumps and natural gas cogeneration plants. At the same time, the specific consumption of natural gas for the generation of thermal energy is more than halved compared to the most efficient gas boilers. Of course, the introduction of such installations requires considerable capital expenditures. But such projects are self-sustaining. 

Replacing natural gas with biofuels Another direction that makes it possible to reduce the cost of heat energy in the SCR and at the same time increase the energy security and independence of our country. The use of biofuels (firewood, wood chips, wood pellets, straw bales, corn stalks, pellets from husk, other agricultural waste) will contribute to the development of the local and regional economy, and at the state level - to improve the trade and payment balance by reducing energy imports. According to the Bioenergy Association of Ukraine (UABio), which is actively implementing the concept of expanding the use of biofuels in the SCT, the cost of biofuels in a number of cases is half the comparable cost of natural gas, which makes it possible to significantly reduce the tariff for thermal energy. The experience of Lithuania confirms this. The average cost of thermal energy from boiler houses on biofuels in 2015-2017 was 27-35% lower than from gas boilers. UABio proposes to create a biofuel market that guarantees its stable supply, as well as to simplify and guarantee the connection of independent heat energy producers to the heating networks of SCT, including those that use biofuels and offer heat energy cheaper than existing producers. 

 

Centralization or decentralization? This issue is periodically actively discussed in wide circles of producers and consumers of thermal energy. Many cities have already abandoned district heating and switched to individual or autonomous systems (Uzhgorod, manganese, Nikopol, Pokrov, Zolochev, Dolina), using the main argument - the ability of the consumer to manage heat consumption and costs for it. However, as will be shown below, such possibility gives and SCT. The choice of a heat supply system is an optimization problem that is solved on the basis of the widely known cost-benefit analysis. At the same time, not only obvious economic indicators, but also environmental, as well as reliability and safety indicators should be considered, taking into account forecasts for the future.There are two main criteria that must be taken into account: the density of buildings (and, accordingly, the density of the heat load), as well as the possibility of obtaining heat energy from alternative sources and cogeneration in a particular area of the city. Instructive history of the emergence of SCT. The first commercial SCT was launched in 1877. in an area with a high density of development Lockport, New York. The history of district heating in Denmark is associated with the municipal district of Copenhagen Frederiksborg and the construction of an incinerator there in 1903, the waste heat from which was sent to the municipal hospital, an orphanage and a nursing home. The history of district heating in Iceland is associated with geothermal energy and dates back to 1908. Today, more than 90% of homes in this country are heated by geothermal energy. The first SCT in Russia (St. Petersburg, 1903) used the heat of the waste steam of the power plant, which was supplied to the children's hospital. In the Soviet period, centralized heat supply became widespread. In those days, along with economic considerations, a certain influence had a political attitude on the general centralization. Therefore, it is now advisable to revise, scientifically substantiate and fix for the long term the zones of centralized and decentralized heat supply, focusing on the above-mentioned factors. Heat supply is centralized, individual regulation It is believed that the main advantage of individual heat supply compared to centralized is the ability to account for and regulate the amount of heat consumed in each apartment. But such an opportunity can be provided in the SCT. In new buildings, individual heat points are installed, providing weather regulation, and in each apartment - regulating valves and heat meters, which make it possible to manage and pay for the actually consumed amount of heat energy. In old houses, as a rule, modernization of intra-house pipe breeding is necessary. 

 

Kharkiv scientists have developed proposals for the arrangement of individual heat supply systems in each apartment of any apartment building connected to the SCT and are actively implementing it in practice. It is necessary that in the implementation of thermal modernization of houses, such systems are introduced that help to organize apartment accounting and regulation of heat consumption. The problem of heat networks It is a bottleneck of district heating systems. The service life of 50% of heating networks exceeds 20 years. Average losses in such networks, determined by calculation, are 19%. The amount of damage to pipes in most settlements reaches critical values. So, in some areas of Kyiv it is 6 damage/year· km despite the fact that in European SCT this indicative does not exceed 0.1. However, the problem of modernization of heating networks is not only in their physical deterioration. The capital costs of their modernization are quite large, and the payback period is at least 15 years. It turns out that replacing pipelines is an unattractive project for investors, and municipalities do not have sufficient financial resources. The solution is a comprehensive approach to the modernization of heat sources (self-sustaining projects) and heat networks (infrastructure projects). Only within the framework of the implementation of complex projects can money be raised for the modernization of heating networks. The problem of reliability of information What cannot be measured, therefore, cannot be controlled, is a known truth. We do not measure the amount of natural gas in units of energy, as is customary in European countries, but in units of volume. In this case, the calculations use some average value of the caloric content of natural gas. At the same time, employees of boiler houses note significant fluctuations in the quality of natural gas coming in different periods of time. 

They cannot confirm their observations with measurement results due to the lack of expensive modern devices (flow calorimeters). Measurement of actual losses in thermal networks by the instrument method is a rather laborious task and is extremely rare in practice. The level of providing heat meters to consumers of thermal energy in our country is quite high - about 80%, but their absence in 20% of consumers does not allow to reduce the actual balance of production and consumption of thermal energy, and therefore to determine the actual losses in heat networks. 

In general, the problem is not only in the absence of certain devices, but also in the absence of regulatory requirements and the usual practice of using actual (measured) data in reporting. In the centralized heat supply, the usual practice of conditional calculation indicators has developed. It is easier to work with them than with the results of actual measurements. And actually, who does not like it? This should not suit those who seriously plan to develop and implement capital-intensive investment projects, invest in the modernization of the SCT, take and give loans. After all, energy indicators, which we talked about, are the basis for calculating financial indicators. A comprehensive analysis of energy and financial indicators is the field of energy management. In our country, the international standard ISO 50001 (Energy management systems - Requirements with guidance for use) is harmonized. It should be actively implemented in the field of district heating, creating structural units of energy management in municipalities and heat supply organizations, and most importantly, to train qualified personnel in this area. Complex approach to thermo-modernization of buildings and SCT Heat sources, networks and buildings connected to them constitute a single complex system. It is the characteristics of houses that determine the connected heat load, the diameters of the pipes of heat networks and the installed capacities of heat sources. Large-scale thermal modernization of buildings (as we hope) will radically change all these parameters. An uncoordinated approach to the modernization of SCT and houses will inevitably lead to the adoption of suboptimal technical solutions and the irrational use of financial resources. Today, in the cities and settlements of Ukraine there are no comprehensive plans for the modernization of the SCR and the houses attached to them. 

In European countries, unified municipal energy plans are being developed, within the framework of which all infrastructure systems of the settlement are considered, including houses, heat, gas, electricity, and water supply systems. Many Ukrainian cities - members of the European Association "Energy Efficient Cities" have already developed such plans. But these documents are outside the legal framework of Ukraine. It is necessary to correct this deficiency, develop and implement such plans. SCTs need state support. These systems were created centrally, and they also need to be modernized centrally. I do not want to make negative forecasts, but with a high degree of confidence it can be argued that without active state support, the negative trend of curtailing the SCR will continue and intensify. Today in Ukraine there is no state strategy for the modernization and development of the SCT. Such a document should have been developed. It is necessary to formulate the main conceptual provisions set forth in this article. As a catalyst, a state program for the modernization and development of SCR is needed, aimed mainly at restoring heat networks. The presence of a state program will serve as a powerful impetus for attracting investment in energy-efficient heat sources. At the same time, equal conditions for access to heat networks should be guaranteed on a competitive basis to suppliers of heat energy of various forms of ownership. 

The strategy and state program should be supported by municipal plans for the long-term development of the SCT, which should be given the status of an urban planning document. Such plans should be associated with municipal programs of thermal modernization of houses. The solution to this problem cannot be postponed. No one can guarantee how long the pipes that have worked in the ground for twenty or more years will last. Rationally using what can still work, it is necessary to gradually replace what can no longer be used on the basis of modern district heating technologies. Answering the question in the title of the article, we can say that the SCT is a rich heritage, which, however, quickly becomes obsolete and which must be rationally used in the near future to create modern efficient heat supply systems that can provide us with thermal energy at prices significantly lower than those that we pay today, simply by burning expensive natural gas in the furnaces of boilers.